Core A will provide cytogenetics and molecular genetics support to the various projects of this application. Karyotype analysis will be provided on all patients' samples as a function of the status of the patient's disease and therapy. In addition, all cell lines maintained in culture or established from patient samples will be analyzed for chromosomal abnormalities or alterations. The need exists for a better understanding of the chromosomal events which occur during initiation and progression of MM so that particular molecular lesions can be targeted for further study. Coupled with the more standard chromosomal analysis, this core will also provide chromosome analysis by fluorescence in situ hybridization (FISH). This approach allows increased sensitivity, speed, less labor and ease of data interpretation when compared to more traditional analysis. FISH will initially be applied to interesting patient samples identified by karyotype analysis and then expanded to additional samples in the latter years of the project. Specifically, FISH will be used to examine for chromosomal abnormalities, such as translocations or deletions, to identify small marker chromosomes, to determine ploidy or aneuploidy to interphase nuclei, and to rapidly localized DNA sequences to individual chromosomes. this core will also provide information about the involvement of oncogenes and tumor suppressor genes in the disease process. In particular, the core will measure mutations in ras, the level of myc expression, alterations in p53 and Rb gene structure, and loss of heterozygosity of chromosome 13 and 17 in MM patients. In addition, we will use PCR for the detection of monoclonal B-cell populations. the detection of residual disease will become important as complete remissions by immunofixation criteria are more frequently achieved with BMT programs. Karyotype analysis will be performed by high resolution G-banding analysis. FISH will utilize biotin-labeled DNA probes for individual chromosomes which will be detected using a double antibody approach. Molecular analysis will be performed by PCR, Northern Blot Analysis, and direct sequences analysis.